session-ios/Signal/src/ViewControllers/PhotoLibrary/PhotoCollectionPickerController.swift

//
//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
//

import Foundation
import Photos
import PromiseKit

protocol PhotoCollectionPickerDelegate: class {
    func photoCollectionPicker(_ photoCollectionPicker: PhotoCollectionPickerController, didPickCollection collection: PhotoCollection)
}

class PhotoCollectionPickerController: OWSTableViewController, PhotoLibraryDelegate {

    private weak var collectionDelegate: PhotoCollectionPickerDelegate?

    private let library: PhotoLibrary
    private let previousPhotoCollection: PhotoCollection
    private var photoCollections: [PhotoCollection]

    required init(library: PhotoLibrary,
                  previousPhotoCollection: PhotoCollection,
                  collectionDelegate: PhotoCollectionPickerDelegate) {
        self.library = library
        self.previousPhotoCollection = previousPhotoCollection
        self.photoCollections = library.allPhotoCollections()
        self.collectionDelegate = collectionDelegate
        super.init()
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    // MARK: View Lifecycle

    override func viewDidLoad() {
        super.viewDidLoad()

        view.backgroundColor = .ows_gray95

        if #available(iOS 11, *) {
            let titleLabel = UILabel()
            titleLabel.text = previousPhotoCollection.localizedTitle()
            titleLabel.textColor = .ows_gray05
            titleLabel.font = UIFont.ows_dynamicTypeBody.ows_mediumWeight()

            let titleIconView = UIImageView()
            titleIconView.tintColor = .ows_gray05
            titleIconView.image = UIImage(named: "navbar_disclosure_up")?.withRenderingMode(.alwaysTemplate)

            let titleView = UIStackView(arrangedSubviews: [titleLabel, titleIconView])
            titleView.axis = .horizontal
            titleView.alignment = .center
            titleView.spacing = 5
            titleView.isUserInteractionEnabled = true
            titleView.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(titleTapped)))
            navigationItem.titleView = titleView
        } else {
            navigationItem.title = previousPhotoCollection.localizedTitle()
        }

        library.add(delegate: self)

        let cancelButton = UIBarButtonItem(barButtonSystemItem: .stop,
                                           target: self,
                                           action: #selector(didPressCancel))
        cancelButton.tintColor = .ows_gray05
        navigationItem.leftBarButtonItem = cancelButton

        updateContents()
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)

        if let navBar = self.navigationController?.navigationBar as? OWSNavigationBar {
            navBar.overrideTheme(type: .alwaysDark)
        } else {
            owsFailDebug("Invalid nav bar.")
        }
    }

    // MARK: -

    private func updateContents() {
        photoCollections = library.allPhotoCollections()

        let sectionItems = photoCollections.map { collection in
            return OWSTableItem(customCellBlock: { self.buildTableCell(collection: collection) },
                                customRowHeight: UITableViewAutomaticDimension,
                                actionBlock: { [weak self] in
                                    guard let strongSelf = self else { return }
                                    strongSelf.didSelectCollection(collection: collection)
            })
        }

        let section = OWSTableSection(title: nil, items: sectionItems)
        let contents = OWSTableContents()
        contents.addSection(section)
        self.contents = contents
    }

    func buildTableCell(collection: PhotoCollection) -> UITableViewCell {
        let cell = OWSTableItem.newCell()

        cell.contentView.backgroundColor = .ows_gray95
        cell.selectedBackgroundView?.backgroundColor = UIColor(white: 0.2, alpha: 1)

        let imageView = UIImageView()
        let kImageSize = 50
        imageView.autoSetDimensions(to: CGSize(width: kImageSize, height: kImageSize))

        let contents = collection.contents()
        if contents.count > 0 {
            let photoMediaSize = PhotoMediaSize(thumbnailSize: CGSize(width: kImageSize, height: kImageSize))
            let assetItem = contents.assetItem(at: 0, photoMediaSize: photoMediaSize)
            imageView.image = assetItem.asyncThumbnail { [weak imageView] image in
                guard let strongImageView = imageView else {
                    return
                }
                guard let image = image else {
                    return
                }
                strongImageView.image = image
            }
        }

        let titleLabel = UILabel()
        titleLabel.text = collection.localizedTitle()
        titleLabel.font = UIFont.ows_dynamicTypeBody
        titleLabel.textColor = .ows_gray05

        let stackView = UIStackView(arrangedSubviews: [imageView, titleLabel])
        stackView.axis = .horizontal
        stackView.alignment = .center
        stackView.spacing = 10

        cell.contentView.addSubview(stackView)
        stackView.ows_autoPinToSuperviewMargins()

        return cell
    }

    // MARK: Actions

    @objc
    func didPressCancel(sender: UIBarButtonItem) {
        self.dismiss(animated: true)
    }

    func didSelectCollection(collection: PhotoCollection) {
        collectionDelegate?.photoCollectionPicker(self, didPickCollection: collection)

        self.dismiss(animated: true)
    }

    @objc func titleTapped(sender: UIGestureRecognizer) {
        guard sender.state == .recognized else {
            return
        }
        self.dismiss(animated: true)
    }

    // MARK: PhotoLibraryDelegate

    func photoLibraryDidChange(_ photoLibrary: PhotoLibrary) {
        updateContents()
    }
}